What Is A Diamond Fluorescence

Fluorescence usually is a white-blue light that some of the diamonds emit. But this effect can only be achieved under special ultraviolet light. This is how the fluorescence shows.
In the diamond mines ultraviolet light is used for finding rough diamonds.
Under normal light they do not emit fluorescence.
Let me explain this more precisely. Boron atoms react to ultraviolet light and that is why diamonds emit fluorescence.
During the diamond growth in the earth, the diamonds are subjected to extreme pressure and heat. Also foreign atoms beside carbon are mixed in the diamond structure. Some of these foreign atoms are also boron atoms that reflect white blue fluorescence under ultraviolet light.

Fluorescence Affect

Each diamond is also measured for the level of fluorescence. Fluorescence does not affect the physical diamond properties. Diamond labs will rate diamonds for fluorescence level from None to Very Strong level of Fluorescence.
The level of fluorescence can affect the color of a diamond under the normal light conditions.  If for example a diamond is slightly yellow it might appear white under normal light conditions.